Oil-concrete roadway.



B. M. GHADBOURNE.

UIL CONCRETE ROADWAY.

ArPLIoATIoN FILED P3312, 1010.

965,562 Patented July 26, 1910.Av

EIWA'PLD M. CHADBOURNE, OF SAN FRANCISCO, CALIFORNA.

GIL-OGNCRETE LELADWY.

,To allfwhom it may concern:

yBe it known thatfI, EDWARnVM. (li-itam minima, a citizen oi. United States, residing al) the city and county of San Francisco and State of California, haveinv'ented new and useful Improvements in Gil-Concrete Read- Ways, of which the following is a 'specificatio This invention relates to highway construction, and pertains especially to an oiled, reinforced concrete road.

The object of the present invention is to provide a` road, street or way which is made of a substantial sub-base and a wearing' cushion which is .dustl'ess, ermanent, and requires very little expense or maintenance,

The special object of the present invention shocks or lows through a Wearing surface is to construct this roadway so that Vthe Wearing surface, which is made up of a mixture ofoil, or like binder, and screenings, and is permanently anchored to the underneath foundations and base, is reinvenated or revitalized Whenever the surface begins to break u or disintegrate, by the elastic element o a certain surplus of a natural liquid binder or a binder which is liquid or viscid at ordinary temperatures.

l street or highway'is a structure built ordinaril ,as is well known, to endure or sustain vt e traiic of moving vehicles, such as automobiles, traction engines', Wagons, etc. This traliic creates forces or loads which a-street 'orhighway must be designed to withstand, according to lconditions or requirements of use. Among these forces or loads are vthe forces of impact which are created by sudden shocks or blows delivered to the street `or highwa from external bodies. These shocks or ivilows may be def' livered by heavy trucks, traction engines,

horses, etc., their effect being impact forces- Whichtend to disintegrate whatever they come in contact with, Therefore, one of the ei'ssentlal requirements for a ,good street orhlghwa 1s that it Vmust be able to absorb `having; elastic properties. ln the selection zofmaterial for the Wearingsurface toab- "Sorb this. force of impact there are many matermls in use today, such as bitumen, asphaltlc compositions, brick, Wooden blocks,

',ete.l Of these `materials asphaltic compositions and bitumen `are used the most for.

.weai'in y properties they cannot Yabsorb impact forces.

surfaces, but on account of their Consequently, they eventually disintegrate, and the street or highway fails because the binder used is a naturally solid or noiiviscous material. li mean by thisthat its natural state is not a liquid, but is a solid, such as the asphalt and asphalt compositions commonly used. Hence, to give Ythlem binding properties they must first be heated to a Y liquid form and then applied in combina-v tion with other materials, such as sand, rock, etc lli/'hen this binder cools oli?, it solidiiies and holds the different particles which it surrounds rigidly, with thei result that surfaces madegup'of' naturally solid hinders are inelastic and will not'standim-4 4pact forces. y

In'my invention which has resulted after many experiments and demonstrations, I use Specication of Letters Patent. Patented July 26, 1910.

Application filed February 12, 1916. Serial No. 543,557.

naturally liquid binders and so place them that they always exert binding forces intor the Wearingr surface, giving, it elasticit and ability to absorb impact forces. In p acin i and holding Ithis naturally liquid binder, have taken into considera-tion a very important point, and that is, that knowing that the naturally liquid binder will iioW out in a way from the aggregate in Wearing'surfaces, I have taken special pains to arrange my roadway so that the` naturally liquid binder is forced into, and a certain excess ofthe binder retained in, the voids in the aggregate of theV Wearing surface, With .the result that my surface is elastic and able to absorb impact forces. l

Correlative with the desideratum ofelasticity'isthat of tenacity, or the quality to resist the forces of suction due to the rapid ci a roadway with a surface that isv as y nearly perpetually elastic as possible, and

also a surface that may, when oxidized or Worn out, have .its vitality and elasticity restored, from a storage of oil, or equiva-- lent, in reservoirs or pockets in the surface of the base and also from the oil-in 4the voids in the screenings in the top surface.

vrHai/ing reference to the accompanying drawings-Figure l 1s a perspectlve view in partial section of a roadway illustrating theV inventionu Fig. 2 is a section in a vertical plane, and Fig. 3 is a sectional :perspective of roadways showing modifications in the y is first laid.

formation of the pockets. Y, u t

A base of plain orrcinforced concrete Before this concrete vbase is t set, and while it is still'in a plastic condition, I form pockets -or reservoirs Vin the` same in several different ways.

One wav is by placing von top of this concrete base,

while it is still plastic, a course of largev rock 2 approximately two to. three inchesin approximately one to three inches.

size. A -good `part of lthis lcourse of rock becomes attached to the concrete base, when iic, a form having small knobs on the un-I der side, and when the same is removed after the concrete is set, pockets or 'reservoirs 2 are formed, as shown inFig. 2. In many cases Lm'ay vary'the size of the storage res-4 ervoirs, making them the widthof'the roadv way, or I lmay make them as small as two v inches in width dimensions.A .In all cases 4the depth of these pockets or reservoirs 1s,

If very little' crown is desired for the roadway, and if the same. is nearly level, I- may form in the concrete base furrows or `canals which serve the same functiony as' vpockets Orreservoirs. In anyvcase,all of the indenta-v tions, grooves, pockets or receptacles in the concrete base, no matter 1n what size or form they lare placed or by what .means made, serve as storage reservoirs for, the oil.

After the concrete base is settlancl the pockets or reservoirs become formed therein by any suitable method., I vflood this base `mately one-half inch in size.

.ished wearing surface.

with, or apply to the surface'of the base a eoating or heavy, mineral foil; which, if heavyasphaltic'oil is used, may be previously heated to make it more viscous.

This oil lls, or'partially-flls, the pockets or concrete base,

reservoirs'in the top ofthe and on account o'tth'e` impervious compositions in thejbasek does not pei-colate downward rand become lost. I next spread a layer of sized screenings'over`the oiled'con,`

crete base these screenings i being approxi- These screenings are as near one' size as possible, as I thus obtain a largerpercentage of voids' in vsame. v These screenings not only -ill the pockets, .but extend two or three inches,

more or less, above the surface of the base, according to the desired depth of the finvThe screenings are then rolled, forcing 'the screenings down into the oil, ypartially displacing `'the oil binder and and durable.` One size of screenings is sulii- 'also i'n 'the voids juvenate f or revitalize `poured in natural fluid .over this liquid forming a permanent inished'A wearing 'surfac'ethat is elastic,l tenacious.

eeasea cient, as Iy have found that alea njscreenings of approximately halt-inch size ,glye excellent results; and the wear that their sur face is subjected to stices filled, and as the oil works upward constantly it binds the whole surface into one monolithic structure possessing the desirable .attributes of elasticity and permanency.; With these sized screenings there is a certain amount of oil inthe ockets that is not" absorbed at first, and *purposely u se these sized screenings soa Ito, 'make a great many small distinct voids to provide oil cavities. The excess'oil in the 'pockets orres'ervoirs on to of the-concrete'basdand and starts to wear away, lthegliquid bindery in the pockets or reservoirs inthe top* o'fthe concrete base 'and also in 'thevoids 1n the n the screenings, makes' the surface as near perpetually *elastic as eps the upper interf lower -course of the screenin' s in the surface rejuvenates or revit'alizes t thus seen very readily that 'as `soon as =one y e wearing "sur-,1 face so4 that 1t' is 4made elastic again. llt iis surface lof* the roadway disintegrate?, `andv wears away, anotherforms bytheaction of the storedoil lubricating and'rebondingthe screenings sgain. This wearing surface wears away ar less rapidlythan a wearing 'surface which has no storage of oiljto ireit, and give it yelasticity when exhausted.

A roadway which is thusconstructed com- `prises a concrete or like 1 impervious base with. pockets in its top suracawith alayer of sized 4screenings thereoveif, and vwith ay .bond of heavy oil orv equivalent naturally, liquid binder, the amount of vthe liquid binder'bein'g in Iexcess of 'that necessary to eo'a't and cement the screenings, this excess,

bein'g .contained in 'the voids orm'ed bythe sereemngs'and lying ontop of the-:concrete y base and l'lingfthepockets; the screenings being rolled to form a lfirm wearingjsurface,

'and the 'excess of ybinder 'contained infthe volds'lgradu'ally working tothe surface to rejuvenate the latter as time goes'on.

4While prefer fto use, for commercial reasons, aheavy asphaltic oil', l may use -any other naturally viscous, or live liquid' or semi-'liquid binder, this y state, or slightly heated to increase its 1impidity,.over the impervious foundati'omand then spreading the.

aggregate inthe 'form ofsized screenings binder having the quality, after'th'e aggregate is rolledto form a wearing surface, of

.not only binding the `particles together, but

hardening from binder being 'rst l binding stratum; 'this drawing upto theH liquid binder gives the desired elasticity and tenacity.

I prefer to use aggregate 1n,the form of irregular sized screenings, smccf the irregular sur .aces tend to interlock and consequently, prevent motion about each other when acted on by external forces. Also, `as yit is advisable to have as much oil or other natural liquid binder in the wearing surface as possible, the percentage of voids in the screenings must be large, and for that reason I refer to use the screenings of approximately halfdnch size, with the result that the voids average about forty per cent. of the volume; this forty per cent. of volume being occupied by the excess of the binder, which excess, as before described, is utilized, when necessary, to revitalize the wearin surface by giving it renewedelasticity an bonding qualities. l

Having thus described my invention, what I claim and desire to secure by Letters Patent is-- 1. A method of roadway construction which consists in laying a mmdation impervious to heavy oils and fornhng its surface into receptacles to prevent escape 1of the oil by drainage .and in applying to said foundation a top layer of oil and smallsize aggregate having a large percentage of'voids filled bylthe'oil, the percentage of oil being in excess in the bottom of the top layer in position to be supplied to the wearing surface by abso tio which consistsin laying a concrete founda- .tion impermeable to liquids and forming dation over'theroadway,

the upper surface of said foundation into receptacles open at the top to retain a natural liquid binder against esca e by drainage, ap lying a` natural lliquid inder to said foun ation, then applying andforci'ngdown into said binder small aggregates by the and binder being such that-the binder is in excess in the layer of aggregates and in position to be absorbed by the wearin surface of vthe roadway to revitalize the latter.

3. The methody of.. roadway construction which consists in forming a concrete founorming pockets in give.. it permanence 2. The method o roadway construction -ing surface by absorption.

' the top of this foundation, loodingthe'surface and oekets with a heavy oil, applying a layer ci) sized screenings and forcing the same down into the pockets and oil,.. said screenings and pockets forming numerous voids to store a surplus lof oil, the relative percentage of screenings and oil being such that the oil is in excess and in position to be absorbed by and rejuvenate or revitalize the Wearing surface.

tion, and whilethe latter -is in a plastic condition forming oil retaining pockets open at the top, pouring a coating of heavy asphaltic oil over the surface to fill the pockets, spreading a layer of screenings apg proximately one-half inch in size over .the

4. The method of roadway construction which conslsts in laying a concrete founda-A foundation, and rolling the screenings to y compress, them and to fill the pockets, the relative percentage of-oil and screenings being such that the oil is in excess and said screenings forming a' multiplicity of voids which act as storage reservoirs for the surplus of oil which is not taken up by absorption, said surplus of oil acting to rejuvenate the wearing surface as time goes on.

. 5.`The method of roadway construction which consists. of laying a concrete foundation, and forming its` surface into numerous pockets or reservoirs, pouring over the sur- 'face of the foundation a naturally liquidl binder sufficient to fill the pockets, then spreading a'layer of sized aggregate over t e surface, which layer of aggre te forms within itself numerous voids an` the percentage of oil being in' excess of that which will be heldby labsorption in the a gregate, the aggregate filling the pockets an extending over the foundation, and rolling this 'aggregate to compress it and to' take u aportion of the 'binder to provide a wearing surface.

6. A pavement for roadways Iembodying a cementitious foundation' impervious to heavy oils Huid at ordinary temperatures and embodying means for preventing the escape of oil by drainage, a top stratum of. comminutedwear resisting material overlying said foundation, and a heavy oil fluid at ordinary temperatures held-in said top stratum and existing in excess in proximity to the foundation, whereby the o1 l will be maintained in posititbn to be fed to the wear- Intestimony whereof I have hereunto set my hand in the presence of two subscribing witnesses. 1 I

EDWARD M. CHADBOURNF. Witnesses:

CHARLES A. -PENFIELm RAYMOND A. LEONARD. 

